Turbulent penetrative and recirculating flow in a compartment fire

A numerical study of a turbulent penetrative and recirculating flow induced by the energy input from a fire at the bottom boundary in a partially open rectangular enclosure is carried out. The compartment is connected through an opening to a long corridor, which opens into a stably stratified environment. The condition that is of interest is a stable, two-layered temperature stratification, which is assumed to be caused by fire in an adjacent enclosure. In this study, attention is focused on the interaction between the cavity and its surrounding ambient medium through the opening. The influence of the stratification is examined in the turbulent flow regime by considering a range of stratification levels for given opening height and initial interface location. It is found that, depending on the stratification, the thermal plume above the fire may never reach the ceiling. Small penetration distances occur al large stratification levels. The pow field reveals a multicellular pattern: a strong main convective cell at the bottom and a weak counterrotating cell at the top. The stable thermal stratification can cause a destruction of the turbulence. This results in the relaminarization of the flow in the upper region of the cavity and may significantly affect the transport processes in the enclosure. This could distort the simplistic concept of two homogeneous gas layers, which forms the basis of zone modeling for compartment fires.